Television system



2 Sheets-She et 1 a; l l l l l INVENTOR ALFRED N. sou) SMlTH %w ATTORNEY June 15, 1936. A. N. GOLDSMITH TELEVISION SYSTEM Filed Aug. 14, 1930 PatentedJune 16, 1936.

PATENT OFFICE TELEVISION SYSTEM Alfred N. Goldsmith, New York, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application August 14, 1930, Serial No. 475,188

9 Claims.

The present invention relates to television systems, and, in particular, to television systems of a type such that it is possible to change from one scene to another without the necessity of interrupting the transmission, and so arranged that the two pictures are mixed or blended during the time when the transmission of one picture is being stopped and the transmission of the other picture is being started. According to motion picture technique, this process has become known as the fading in and fading out? process, or, when these occur simultaneously, as\

"lap dissolves. It has long been recognized that it is more pleasing to the eye to view a picture where the scene is changed by the gradual disappearance of one scene and the gradual appearance of the other than to change abruptly from one to another scene, either sequentially or concurrently, and it is a principal purpose and object of the present invention to provide ways and means for accomplishing this desirable result.

By the accompanying drawings which form a part of my present disclosure, when read in conjunction with the following specification and claims, I have shown several embodiments of systems adapted and suited to carry out the purposes of this invention, wherein:

Fig. 1 illustrates one form of system wherein the fading in and fading out is controlled in accordance with the amount of useful energy which may be drawn from a plurality of separate photo cell amplifiers;

Fig. 2 discloses a modification wherein the intensity of the illuminating source for each of the two pictures is controlled;

Fig. 3 discloses a modification of the arrangement shown by Fig. 2 wherein the useful light from each source of illumination which reaches the picture may be controlled;

Fig. 4 still further modifies the construction shown by Fig. 3 and controls the amount of useful light which may reach independent photo cell amplifiers; and,

Fig. 5 illustrates one form of screen suitable for use in connection with the showing of either Fig. 3 or Fig. 4.

According to the present invention, I have provided two independent transmitter assemblages, and have parallelly connected the output of each so that one or the other or both, in varying degrees, each may influence an appropriate amplifying system. According to various modifications, the amount of energy from each of the photo cell amplifiers may be controlled in various ways, for example the output strength may be controlled through the use of suitable potentiometers arranged in the output of each of the photo cell amplifiers and so designed and constructed that as the useful output of one is decreased, the useful output of the other is increased, and vice versa. Also, it is possible to construct and arrange the system in such a manner that the illumination upon one of the two subjects is being increased while being decreased on the other, and vice versa, so as to control the current flowing in each of the photo cell amplifiers. A still further means for controlling the fading in" and fading out" of two separately transmitted picture subjects may be provided by means of screens arranged either to dim the light from one source while increasing the light from the other, or vice versa, or by dimming or increasing the amount of useful light reaching the photo cell amplifier, so that the current flowing therethrough may be of strength proportionate to both the intensity of light and shadow of the picture, and the degree of illumination of the subject as can affect the photo cell amplifier.

To refer now more particularly to the drawings, I have shown two separate subjects, A and B, which are to be transmitted, so that if it is assumed that the subject A has been transmitted, and it is desired to change the transmission from subject A to subject B, the image produced by subject A may be brilliant, then dim and finally disappear, while the image corresponding to subject B is first invisible, then dim, and then finally appears with maximum brightness at the receiver end of the system. In accordance with this provision, I have provided a source of illumination I for illuminating subject A and a separate source of illumination 3 for illuminating subject B. The source 1 preferably comprises an are formed from electrodes 5 and I, so arranged that the light issuing therefrom, when the electrodes are connected by means of conductors 9 and II with a power source connected to the terminals 2| and 23, will be focused upon the image A. Where desired, suitable lens, mirror, or combined systems may be used, although it is sometimes found that the intensity of the arc source is, of itself, sufficient to properly illuminate the subject. If desired, reflectors 6 of the type shown by Fig. 2 may be used in conjunction with the arc. Similarly, for illuminating subject B by means of the are 3, I have provided electrodes l3 and I5 similarly connected through conductors l1 and ill to the terminals 2! and 23 of the power source. As shown, these light sources will continually emit light toward the subject, although, where desired, I may provide suitable switches for disconnecting either or both of the arcs from the power line connected at 2| and 23.

In the transmission of the subject A, the subject may be suitably focused by means of a lens 25 (although the lens is not essential) upon a scanning disk 29 capable of rotation upon a shaft 30 in the direction shown by the arrow. The scanning disk 29 may be of the usual Nipkow type provided with either lenses or apertures arranged in a spiral path. As the image of the subject A is focused upon the disk 29, due to the rotation of the disk element, successive elemental areas of the object are caused to influence the photo cell 3| to varying degrees of light and shadow. Through the conductors 33 and 35 this cell is suitably connected with a photo cell amplifier 4|. Anode potential for the cell is supplied by means of a battery 31, and as the varying intensities of light and shadow reach the cell, these suitably control the grid potential of the amplifier 4| by reason of the varying potential drops produced in the resistor 39 shunting the amplifier input circuit. The output energy from the amplifier 3| is connected by means of a conductor 43 to one terminal 45 of a potentiometer having a resistance element 41, to the opposite end of which at 49 is connected the plate battery for the amplifier. A suitable control element 5| is rotatably mounted at a point 53, so that as the conductor terminal 81 thereof contacts with various points on the resistance portion 41, varying strength currents will flow in the conductor 55 connected to the center terminal 53 so as to pass through the primary Winding 51 of the transformer 59. The secondary 6| of the transformer 59 is appropriately connected with a modulator which is so arranged that it may appropriately modulate a suitable carrier frequency for transmission of the picture point energy either by radio or wire line.

Similar to the arrangement shown in connection with the transmission of the image A, I may provide a lens 21 for focusing the image B upon the disk 63 which is arranged to rotate about the shaft 65 in the direction shown by the arrow. Light values proportionate to the intensity of light and shadow upon each elemental area of the image l3 are fed through suitable conductors 69 and H to the input circuit of the amplifier 11. The photo cell 61 is provided, similarly to the cell 3|, with a suitable source of anode potential, and across the input circuit of the amplifier TI is connected a resistor 15, similar to that shown at 39 in connection with the amplifier 4 I. The output of the amplifier TI is connected through the conductor 19 to a terminal 8| of a second potentiometer including a resistance element 32 having its opposite end 83 connected to the plate energy supply source for the amplifier 11. The terminals 83 of the resistance element 82 and 49 of the resistance element 41 are connected in the usual manner, so that there will be a return circuit for the primary 51 of the transformer 59 to either amplifier 4| or 11. As the conductor member 5| is rotated in either clockwise or counter-clockwise direction, depending upon whether it is desired to cause the picture subject A to gradually disappear and picture subject B to gradually appear, or vice versa, the current flowing from either amplifier 4| or 11 passes through a greater or lesser portion of the resistances 41 and 82. Thus, with the conductor element 5| in the position shown, and assuming the contact arm 5| to be moving counterclockwise, so that it makes contact at 31 with resistance 41, and at 33 with resistance 32, it will be observed that picture subject A has substantially disappeared, while picture subject B has influenced the modulator and transmitter to approximate the maximum extent. It is, of course, apparent that the maximum influence of each of the photo cells 3| and 81 and their amplifiers 4| and 11 in the direction shown will be determined by a further counter-clockwise rotation of the conductor member 5|, so that the ends 31 and 33 thereof respectively are at the points 49 and 8| respectively. In this case, picture A will have completely disappeared and picture B will be the picture being transmitted. If it is desired to later change the transmission from picture B to picture A, the potentiometer conductor element 5| is then rotated in a clockwise direction and picture B disappears while picture A appears.

It is, of course, recognized that this arrangement may, to some extent, affect the frequency characteristics of the system. However, to overcome this difiiculty any suitable and well known form of mixer may be used as a compensator for the change in frequency.

Now referring to Fig. 2, I have provided a simi lar arrangement to that shown in connection with Fig. 1 for illuminating each of the picture subjects A and B, and this is preferably provided by means of intense sources of light 2 and 4 which are focused by means of reflectors 6 and 8 upon the picture subjects A and B respectively. As was shown by Fig. 1, the photo cells 3| and 61, responsive to either pictures A or B, are connected through suitable amplifiers 4| and 11. However, as shown by Fig. 2, the effective current strength from the two amplifiers 4| and I1 is not controlled, and the outputs thereof are suitably connected through the same conductors 43 and 19 to the primary winding 51 of the transformer 59, whose secondary element 6| is connected with the modulator and transmitter in the manner described in connection with Fig. 1. In the present instance, in order to suitably control the transmitter, and to determine which of picture subjects A and B is to be transmitted, and to control the varying strength of transmission dependent upon each of the subjects, I have provided in the supply line to the light sources 2 and 4 suitable rheostats 9| and 93 controlled from a common control element rotatably mounted at 95. As shown, it will be observed that the source 4 is more intense than the source 2, and, therefore, the strength of picture subject B as transmitted is greater than picture subject A. Now, if it is desired to cause picture subject A to disappear completely, the control element of the rheostats 3| and 93 will be still further rotated in a counterclockwise direction, so that there ls a maximum amount oi resistance in series with the conductor 9 connecting the source 2 with the power line terminals 2| and 23, and a minimum amount of resistance in the line I connecting the source 4 with the terminal 2| which is connected to the power line. It is thus observed that this likewise provides a most convenient arrangement for causing one picture subject to fade out while the other fades in.

According to the showing in Figs. 3 and 4, I have still further modified the arrangement by providing a system wherein it is neither necessary to control the intensity of the illumination nor the output of the photo cell amplifier .directly. This has been provided by means of a rotatable disk element of the type shown by Fig, 5. This disk so arranged that at one portion thereof it is gmpletely black, and then tracing the figure in a counter-clockwise direction, this black gradually fades into a dark gray, then to a middle gray, then to a light gray, and finally to a plain white. It is, therefore, observed that in one position the disk 91 or 99 will completely block all light which reaches the same, while in a position substantially 360 therefrom substantially all of the light reaching the disk passes therethrough, and for intermediate pulses the amount of light passing through the disk is suitably varied.

In accordance with the showing of Fig. 3, I have provided an arrangement such that there is a disk 91 placed in front of the light source I, and a disk 99 placed in front of the light source 9, so as to control the amount of light from each of these sources which reach the picture subject A or B. The disk 91 is arranged to rotate about the shaft iill, while the disk 99 is arranged to rotate about the shaft I03. When the disks are constructed in accordance with the showing of Fig. 5, it is, of course, desirable to have them arranged such that they may be moved by means of a common element such as a connection shown in dotted lines at I05. With such an arrangement, as one disk is changed from white to black, the other disk changes from black to white. Thus, in order to provide a means such that light reaching picture A is gradually decreased, while the light reaching picture B is gradually increased, one disk 91 is arranged to rotate in a clockwise direction while the disk 99 is arranged to rotate in a counter-clockwise direction, whereas if the intensity of picture B were being decreased while that of picture A was being increased, the disk 91 would be rotated counterclockwise and the disk 99 clockwise. This may be provided most conveniently by means of any suitable gearing and any suitable control therefor.

Instead of the disk mechanism of Figs. 3 and 4 for producing the fade in and fade out, where desired, I may substitute any well known form of dissolving diaphragm or shutter as is known from motion picture technique.

Now making reference to Fig. 4, the arrangement disclosed therein is substantially a duplication of that shown by Fig. 3 with the exception that the disks 9! and 99 carried by the shafts Illi and I99 are arranged to rotate directly in front of the photo cells 3! and 61 so that they permit a greater or lesser amount of light from the picture subject A or B to influence either or both of the cells.

While the invention has hereinabove been described particularly in connection with scanning elements of the Nipkow disk type, it is, of course, obvious that the invention is not limited to the specific structure shown, since it falls clearly within the spirit and scope of the present invention to substitute for the Nipkow spiral disks any other known type of scanning elements, such as the Braun tube used for transmission, mirror disks arranged to suitably rotate and scan a picture subject, rotating tapes, drum disks or oscillating mirrors, or, in fact, any and all known types of transmission systems. It is, therefore, to be regarded that I have merely for convenience of illustration shown a scanning element as comprising a disk. rather than to illustrate it by any other form. However, I believe myself to be entitled to use any form of scanning element which is to be found suitable, and may, therefore, replace the scanning disk by any of the above named types of scanning elements.

Many other modifications not herein shown or described may at once suggest themselves to those skilled in the art to which the invention relates, and I believe myself to be entitled to make and use any and all of these modifications provided. of course, they fall fairly within the spirit and scope of the present invention as has been hereinafter set forth by the appended claims.

Having now described my invention, what I claim and desire to secure by Letters Patent is the following:

1. In a system for transmitting images, the method of changing the transmission from one image representation to a different image representation which includes the steps of projecting a plurality of light images upon scanning devices, dividing the images into a plurality of independent elemental areas to cause the production of image signals representative of each, and decreasing the intensity of one signal while increasing the intensity of the other signal during the period of transition to cause the prior image to fade-out and the subsequent image to fade-in at points of reception.

2. In a system for transmitting images, the method of changing the transmission from one image representation to a different image representation which includes the steps of projecting a plurality of light images upon scanning devices, dividing the images into a plurality of independent elemental areas to cause the production of image signals representative of each, and modifying the intensity of each light image during the transition period to cause one signal output to increase and the other signal output to decrease.

3. In a system for transmitting images, the method of changing the transmission from one image representation to a different image representation which includes the steps of projecting .a plurality of light images upon scanning devices,

dividing the images into a plurality of independent elemental areas to cause the production of image signals representative of each, and varying the intensity of the signals produced from each image during the transition period so that one signal intensity increases and the other signal intensity decreases.

4. In a system for transmitting images, the method of changing the transmission from one image representation to a different image representation which includes the steps of illuminating each of a plurality of subjects of which the image representation is to be produced, projecting light representative of the light values on each subject upon scanning devices, dividing the images into a plurality of independent elemental areas to cause the production of image signals representative of each, and changing in inverse order the intensity of the light illuminating each subject so as to produce resulting image signals of increasing magnitude to represent one subject and the production of signals of decreasing magnitude to represent the other subject during the transition period.

5. In a system for producing electro-optical representations of subjects located at a point of transmission and for changing the transmission from one to another of a plurality of different subjects, a plurality of scanning devices for analyzlng each of a pair of light images representative of the subject during the period of changing a from one to the other so that the light images are divided during the analyzing period into a plurality of elemental areas to cause the production of signal output from the system, means co-operatively associated with each scanning device to convert the light values into electric current impulses, and means co-operating with said analyzing systems and interlocked with each for producing a decrease in the intensity oi the useful output current from one system and an increase in the intensity of the useful output current of the other systems to cause one image representation to fade-out and the other image representation to fade-in.

6. In an electro-optical system for producing fade-in and fade -out of images during the changing of one image transmission to a different image transmission, a plurality of scanning systems for converting the intensity of light and shadow of elemental areas at each of the images into proportional strength electric current impulses by dividing each of the images into a plurality of elemental areas, and scanning the elemental areas according to a pre-established scanning pattern, and means co-operating with each of the scanning systems and interlocked with each other for controlling the strength of the current output therefrom so that the current impulses produced by one system decrease in intensity with an increase in the current impulses from the other system during the transition period.

'7. In an electro -optical image producing system for producing fade-in and fade-outs of images during the change from one image transmission to a different image transmission, a plurality of light sources for illuminating each of a plurality of subjects of which the electro-optical image representation is to be produced, a plurality of scanning systems subjected to the light values of each of the plurality of subjects, said scanning systems being arranged so as to analyze each of the light images by dividing each image into a plurality of elemental areas which are scanned according to a pre-established pattern of scanning to cause the production of electric signal impulses of magnitude proportional to the light brilliance of the several elemental areas, a combined output circuit for the scanning systems and interlocked means for decreasing the light intensity falling upon one of the subjects of which the electro-optical image representation is to be produced and for increasing the light brilliance talling upon the other subject of which the electrooptical image representation is to be produced so that during the transition period the resulting current impulses representative of each of the subjects causes the fade-in and fade-outs of the electro-optical representations produced at suitable receiving points.

8. In a system for transmitting images, the method of changing the transmission between one predominating image representation and a different predominating image representation which includes the steps of projecting a plurality oi light images upon scanning devices, dividing the images into a plurality of independent elemental areas to cause the production of image signals representative of each, varying the intensity of the signals produced from each image during the transition period so that one signal intensity increases to a predetermined level and the other signal intensity decreases to a. predetermined intensity level and subsequently transmitting the predominating image in conventional manner.

9. In a system for transmitting images, the method of changing the transmission between one. predominating image representation of a subject and a difierent predominating image representation of a different subject which includes the steps of projecting the plurality of light images of the subjects upon scanning devices, dividing the images into a plurality of independent elemental areas to cause the production of image signals representative of each, and varying the intensity of the signals produced from each image during the transition period so that one signal intensity increases to a predetermined level and the other signal intensity decreases to a predetermined intensity level.

ALFRED N. GOLDSMITH. 

